Japanese Patent No. 4165375 describes a heating device that heats and shrinks a reinforcing member protecting a fusion-spliced portion of optical fibers to reinforce the fusion-spliced portion. The heating device includes a heating unit (heater) formed by a planar heating element which is bent to have a substantially U-shaped cross section. The planar heating element has a central heating portion which is a U-shaped bottom portion in surface contact with the reinforcing member held therein, and side heating portions which are both side portions not in contact with the reinforcing member. The heating temperature of the side heating portions is lower than that of the central heating portion.
To shorten the time to heat the reinforcing member, it has been recently required, for example, to reduce the thermal capacity by using a planar heating element as a heater as in Japanese Patent No. 4164375, or to set the heating temperature to a high value. However, using a planar heating element reduces the amount of heat generated by the heater per unit time and increases the time to reach a desired heating temperature.
The lower the voltage applied to the heating device, the smaller the amount of heat generated by the heater per unit time. Therefore, when the voltage applied to the heating device is low, it is necessary to increase the heat generating time of the heater to achieve a desired heating temperature. This results in an increase in the amount of power consumed by the heater to heat one reinforcing member. If the heater is supplied with power from a battery, the battery may be exhausted before completion of the heating process.